Computers are vulnerable to malicious computer code such as worms, viruses and Trojan horses. As used herein, “malicious computer code” is any code that enters a computer without an authorized user's knowledge and/or without an authorized user's consent. A worm is a type of malicious computer code that is self-replicating. A worm makes copies of itself, and spreads from one computer to another. Various measures can be taken to protect computers from “infection” by worms and other malicious computer code, but sometimes network administrators and/or individual users neglect to take some or all of these measures, thereby leaving computers vulnerable. On a large network it can be prohibitively labor intensive to manually determine which computers are vulnerable.
In addition to spreading across a network from one computer to another, malicious computer code such as a worm can execute harmful functionality, for example deleting files, sending unauthorized e-mails, or changing system configuration information. Although certain measures can be taken to reduce vulnerability to such threats, it can be prohibitively labor intensive to attempt to determine the extent to which specific computers on a network are vulnerable to which threats. Even where such an attempt is made, the findings tend to be imprecise and incomplete, thus preventing an efficient deployment of security solutions to vulnerable computers.